The longest continuous underground freeway in Australia has opened to Sydney motorists.

The M4-M8 link is expected to take tens of thousands vehicles off Parramatta Road each day and allow drivers to skip around 50 traffic lights.

Terry Chapman has helped build most of Sydney’s major road projects, dating back to the Harbour Tunnel.

He joined Deborah Knight to explain how the tunnel was created.

Press PLAY below to hear the interview